Brake dive compensator

ABSTRACT

The description relates to a braking dive compensator for single-track vehicles. The front wheel (7) with its axle (13) and a brake anchor plate (1) are arranged on a trailing link (4). The link (4) is supported via a sprung component (8) on one fork (3) and, on braking, a force counteracting the braking dive force is taken from the brake anchor plate (1) and the fork (3). Between the brake anchor plate (1) and the fork (3) is articulated a pushrod (2) which assumes an acute angle (α) with the longitudinal axis of the link (4) under tension.

BACKGROUND AND SUMMARY

The invention relates to a brake dive compensation device for the frontwheel suspension of a single-track (two-wheeled) vehicle.

Front wheel suspension systems for single-track vehicles are usuallydesigned with telescopic forms, pushed swinging arms, or pulled swingingarms. By contrast with designs with pushed swinging arms and telescopicforks, a drawn swinging arm has the advantage that the suspensionresponds better to uneven ground, since the direction of the forcecomponents which arise when driving over uneven ground, in the case ofdrawn swinging arms, lie approximately in the direction of movement ofdrawn swinging arms, while with pushed swinging arms or telescopic forksthe force components occur obliquely to the direction of movement of thepushed swinging arms or telescopic forks respectively.

The disadvantage of the design with drawn swinging arms, however,resides in the fact that the spring suspension dives especially deepwhen the front axle is braked. In the case of telescopic forks andpushed swinging arms, this effect is less strongly marked, especiallysince pushed swinging arms counteract the dive effect.

DE 38 33 880 A1 already relates to systems for preventing diving. FIGS.1, 2, 4 and 5 show arrangements with drawn swinging arms, of which FIGS.1, 2 and 4 show arrangements with a rim brake, and FIG. 5 an arrangementwith a drum brake. The explanations for FIG. 5 do not, however, allowfor the functional method of this design to be appreciated.

The invention is based on the task of improving a brake divecompensation arrangement for a front wheel suspension system of asingle-track vehicle in such a way that reliable compensation isachieved for the diving forces which occur during braking, without thespring travel and the spring characteristics being restricted in theprocess.

This task is resolved in the form of a brake dive compensation deviceaccording to the present invention.

In the design according to the invention, the brake carrier is notsupported on the swinging arms but on the wheel guide carrier, with theresult that the force which is exerted by the wheel guide carrier due tothe braking procedure is conducted into the wheel guide carrier, and thelinkage combination of swinging arm, wheel guide carrier, brake carrier,and thrust rod always creates a resultant force in the wheel guidecarrier which precisely counteracts the dive force because of the wheelload which occurs during braking.

As a result of this, spring suspension comfort is fully retained evenduring braking, and, in addition to this, so too is the run-on of thefront wheel, which guarantees constant steering stability.

For preference, the thrust rod, with the vehicle under staticoperational loading conditions, points at approximately right angles toa radial central axis of the brake carrier.

The term "static operational loading conditions" is understood to meanthe state under which the dead weight of the vehicle and the weight of adriver, for whom the suspension has been designed, take effect on thesuspension of the front wheel, either at a standstill or at a constantspeed. The drawn swinging arms with the spring element then adopt aposition in which the spring reserves are approximately equal in bothdirections. This position is also designated as the zero position.

When the thrust rod, with the vehicle under static operational loadconditions, is pointing approximately tangential, the device fluctuatesabout the tangential position as the load is imposed on the suspensionand then relieved, with the result that, to a large extent, linearitycan be guaranteed for the force which is to be applied to compensate forbrake dive.

According to another embodiment, provision can be made for severaljointed connection points on the wheel guide carrier for optionalsecuring of the thrust rod. In this way, the angle alignment can beslightly changed, with the result that adaptation is possible, forexample, to drivers of differing sizes and weights. Depending on size,seat height, and weight of the driver, a different static centre ofgravity will be derived, which then in turn also influences the dynamicwheel load distribution during braking.

For preference, the wheel guide carrier is subdivided into an uppersection and a lower section, which is angled off from the upper sectionin the direction of travel, and the spring element is arranged axiallywithin the upper section. This arrangement allows for an especiallycompact design, since on the one hand the hollow space of the wheelguide carrier is used to accommodate the spring element, and, on theother, the force induced via the spring element into the wheel guidecarrier is imposed axially, with the result that no transverse forcesare incurred.

The lower end of the spring element can be connected by a jointed linkto the swinging arm in the direction of travel in front of or behind thewheel axle or at the brake carrier. The result of this is that thebearing between the spring element and the swinging arm or the brakecarrier respectively can be spatially separated from the bearing,between the brake carrier and the swinging arm, with the result that thebearings can lie in one plane, so making the design more streamlined. Ifthe lower end of the spring element is connected by a jointed link tothe swinging arm in the direction of travel, in front of the wheel axle,then a reduction occurs of the wheel stroke to the spring stroke, withthe result that the spring travel, and therefore also the installationlength of the spring element, can be reduced.

The spring element may include an adjustment device for the adjustmentof a constant zero position under the effect of differing staticoperational loads. This allows for the zero position of the springelement and the swinging arm to be adjusted also for extremely light orextremely heavy drivers, whose weight differs substantially from anormal weight of about 75 kg, for which the spring suspension isdesigned as standard.

The jointed contact points of the swinging arms with the wheel guidecarrier, of the brake carrier with the swinging arms, and of the thrustrod with the brake carrier and the wheel guide carrier, are designed assliding or rolling bearings. This guarantees an especially lightresponse to the spring suspension even in the event of slight orshort-corrugated irregularities in the surface and likewise improves thecompensation for the brake diving forces in the event of load changes.

The wheel guide carrier can be designed as a single-limb or double-limbarrangement. In the single-limb design, the problem of precise matchingof the spring characteristics of the two spring and damper elements isdone away with, which, in the event of no synchronisation beingprovided, could lead to incorrect tilting, and thus to a sluggishreaction.

In the two-limbed design, the spring and damper elements and thebearings can be of simpler and lighter design format, since the forcesare distributed symmetrically.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in greater detail below, on the basis of anembodiment represented in the drawings.

FIG. 1 shows a side view of the front section of a bicycle with thebrake dive compensation arrangement according to the invention, butwithout the frame and handlebars being shown; and

FIG. 2 schematically shows a front view of a brake dive compensationdevice according to an embodiment of the present invention including atwo-limb wheel guide carrier.

DETAILED DESCRIPTION

The brake dive compensation device comprises a single-limb wheel guidecarrier 3, which is divided into an upper section 11 and a lower section12. The lower section 12 is angled in the direction of travel, forwardsin relation to the upper section 11. A swinging arm 4 is attached by ajointed connection to the lower end of the wheel guide carrier 3, which,at its other end, accommodates a wheel axle 13 for a front wheel 7. Thejointed connection point of the swinging arm 4, with the wheel guidecarrier 3, is located in the direction of travel in front of the wheelaxle 13. This type of swinging arm is designated as a pulled swingingarm, and is characterized by an especially light response to unevennessof the ground.

The lower end of a spring element 8 is connected in front of the wheelaxis 13 by means of a jointed link, which extends coaxially upwards tothe upper section 11 of the wheel guide carrier 3, and is located in thecarrier at the upper section 11. The upper part of the spring element 8is connected by a jointed link to the wheel guide carrier 3. The springelement 8 is provided with an additional damper element.

In addition to this, a brake carrier 1 is arranged at the swinging arm4, which in this case supports the brake calliper of a disk brake. Thebrake carrier 1 is supported about the wheel axis 13, in such a way asto be capable of slewing about this axis, and by means of a thrust rod 2which is attached by means of a jointed connection between the brakecarrier 1 and the wheel guide carrier 3. In addition to the jointed linklocation shown, it is also possible to make provision for furtheradjacent jointed link locations 10, to which the thrust rod 2 can beoptionally secured by jointed links for the purpose of compensating fordifferent static centers of gravity.

The thrust rod 2 forms an acute angle α with the axis of the drawnswinging arm 4. The angle α is selected in such a way that the acuteangle is retained throughout the entire spring range. As a result ofthis, the thrust rod 2 is able at all times to exert a spreading forceon the angle β formed between the swinging arm 4 and the wheel guidecarrier 3.

In addition to this, the thrust rod 2, with the vehicle under staticoperational load conditions, is located at an approximate right angle toa central axis 9 of the brake carrier 1, the central axis running in aradial direction. When the device fluctuates between spring compressionand spring extension about the tangential position, a high degree oflinearity of the effect of the brake dive compensation is achieved.

The brake dive compensation device works as follows. When the frontwheel brake is actuated, a tangential force is transferred from thebrake disk 14 onto the brake carrier 1, and this is then imposed via thethrust rod 2 transversely into the upper area 12 of the wheel carrierguide 3. This force leads to a situation in which a spreading forceoccurs between the wheel guide carrier 3 and the drawn swinging arm 4,this force attempting to increase the assumed angle β and so relieve theburden on the spring element 8. A force component 5 is thereforederived, which is directed vertically upwards.

At the same time, the change in the dynamic wheel load into the forwardsdirection leads to a dive force 6 being exerted, the effort of whichtends to cause the spring element 8 to dive, and to reduce the angle βbetween the wheel guide carrier 3 and the swinging arm 4. If correctlyadjusted, these forces 5, 6, offset one another, irrespective of theirabsolute values. As a result, the angle between the swinging arm 4 andthe wheel guide carrier 3, and the position of the spring element 8,remain constant. Additional forces, however, such as may arise whenuneven ground is driven across, as before still cause the springcompression and extension of the swinging arm 4 and the spring element8.

In the embodiment shown, the site of articulated linkage of the thrustrod 2 on the brake carrier 1 is located at the same distance from thewheel axle 13, on which the brake pads engage at the brake disk duringthe braking procedure. The angle enclosed between the thrust rod 2 andthe wheel guide carrier 3 is, in this context, approximately a rightangle. Compensation of the brake dive forces can, however, also beachieved if the distance from the location of the jointed link of thethrust rod 2 on the brake carrier 1 from the wheel axle 13 is increased,and the angle α between the thrust rod 2 and the swinging arm 4 islikewise enlarged, or, conversely, the distance between the location ofthe jointed link of the thrust rod 2 on the wheel carrier 1 from thewheel axle 13 is reduced, and the angle a between the thrust rod 2 andthe swinging arm 4 is likewise reduced.

The exact adjustment of the interval and the angle α can be determinedempirically or by calculating the force components, taking into accountthe design of the vehicle as a whole.

The brake dive compensation device according to the present inventioncan be designed as a single-limb element or, as seen in FIG. 2, as atwo-limb element.

We claim:
 1. A brake dive compensation device for a front wheel springsuspension of a single-track vehicle, in which a front wheel of thevehicle including a wheel axle and a brake carrier, comprising:a wheelguide carrier; a spring element; a drawn swinging arm attached to awheel axis and a brake carrier including a brake of a front wheel, theswinging arm being supported by the spring element on the wheel guidecarrier; a thrust rod connected by a jointed link at one point to thebrake carrier and by a jointed link at another point to the wheel guidecarrier; and the spring element having a spring range and the thrust rodbeing arranged such that, when a force is imposed onto the wheel guidecarrier during actuation of the brake to counteract a brake dive force,within a entire spring range, the thrust rod adopts an acute angle witha longitudinal axis of the swinging arm.
 2. A brake dive compensationdevice according to claim 1, wherein the thrust rod is arranged at anapproximate right angle to a central axis of the brake carrier, the axisrunning in a radial direction, when the vehicle is under staticoperational load conditions.
 3. A brake dive compensation deviceaccording to claim 1, wherein the wheel guide carrier includes aplurality of jointed link locations for connection of the thrust rod tothe wheel guide carrier.
 4. A brake dive compensation device accordingto claim 1, wherein the wheel guide carrier includes an upper sectionand a lower section, the lower section being offset in a direction oftravel relative to the upper section, and wherein the spring element atleast partially disposed inside the upper section.
 5. A brake divecompensation device according to claim 1, wherein an upper end of thespring element is attached by a jointed link to the swinging arm.
 6. Abrake dive compensation device according to claim 1, wherein the springelement includes a damping element.
 7. A brake dive compensation deviceaccording to claim 1, wherein the spring element is adjustably connectedto the wheel guide carrier for maintaining a constant zero position atdifferent static operational loads.
 8. A brake dive compensation deviceaccording to claim 1, wherein jointed link connections are provided toconnect the swinging arms with the wheel guide carrier, the brakecarrier (1) with the swinging arm, a the thrust rod with the brakecarrier and the wheel guide carrier, and the jointed link connectionsinclude slide or rolling bearings.
 9. A brake dive compensation deviceaccording to claim 1, wherein the wheel guide carrier is a single-limbelement.
 10. A brake dive compensation device according to claim 1,wherein the wheel guide carrier is a two-limb element.
 11. A brake divecompensation device according to claim 2, wherein the wheel guidecarrier includes a plurality of jointed link locations for connection ofthe thrust rod to the wheel guide carrier.
 12. A brake dive compensationdevice according to claim 2, wherein the wheel guide carrier includes anupper section and a lower section, the lower section being offset indirection of travel relative to the upper section, and wherein thespring element at least partially disposed inside the upper section. 13.A brake dive compensation device according to claim 3, wherein the wheelguide carrier includes an upper section and a lower section, the lowersection being offset in a direction of travel relative to the uppersection, and wherein the spring element at least partially disposedinside the upper section.
 14. A brake dive compensation device accordingto claim 2, wherein an upper end of the spring element is attached by ajointed link to the swinging arm direction of travel before or behindthe wheel axis (13), or at the brake carrier (1).
 15. A brake divecompensation device according to claim 3, wherein an upper end of thespring element is attached by a jointed link to the swinging arm.
 16. Abrake dive compensation device according to claim 2, wherein the springelement includes a damping element.
 17. A brake dive compensation deviceaccording to claim 2, wherein the spring element is adjustably connectedto the wheel guide carrier for maintaining a constant zero position atdifferent static operational loads.
 18. A brake dive compensation deviceaccording to claim 2, wherein jointed link connections are provided toconnect the swinging arms with the wheel guide carrier, the brakecarrier (1) with the swinging arm, a the thrust rod with the brakecarrier and the wheel guide carrier, and the jointed link connectionsinclude slide or rolling bearings.
 19. A brake dive compensation deviceaccording to claim 2, wherein the wheel guide carrier is a single-limbelement.
 20. A brake dive compensation device according to claim 2,wherein the wheel guide carrier is a two-limb element.